4. Two mark exercise problems I

In \( \Delta ABC\), \(D\) and \(E\) are points on the sides \(AB\) and \(AC\) respectively such that \(DE \parallel BC\) if $\frac{\mathit{AD}}{\mathit{DB}}=\frac{3}{4}$ and \(AC = 15 \ cm\), find \(AE\).